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From: TSS ()
Subject: Review panel rubber stamps US research lab's TSE wastewater disposal practices (Ames, Iowa)
Date: February 25, 2007 at 7:21 am PST

Review panel rubber stamps US research lab's TSE wastewater disposal practices (Ames, Iowa)

NADC's waste treatment unsupported by science


In late February 2006, USDA employee Richard Auwerda blew the whistle on a federal animal disease research lab's practice of flushing TSE-contaminated wastes down floor drains that eventually discharge to the Ames, Iowa wastewater treatment plant. In response to concerns from the Ames city government, the USDA agreed to fund and create a "scientific review panel" to assess the human health risks arising from the federal facility's wastewater practices. A key charge to the panel was to identify "scientifically accepted methods for effectively destroying prions in waste water." Prior to discharge to the city's treatment plant, wastewater from the research facility undergoes a "steam sterilization" treatment process. Logically, one would expect that the review panel would survey the scientific literature for evidence supporting or challenging the efficacy of the steam sterilization process, and that this evidence would be described in the panel's report. The report's authors, however, simply assert that steam sterilization is an "accepted" method for TSE disinfection without providing supporting data. Based on the available science, it is fair to assume that the process reduces TSE infectivity, but there can be no reasonable assurance that detectable amounts of scrapie, CWD, TME, and BSE infectivity are not escaping the treatment process and entering the Ames wastewater treatment plant. JW

Evaluation of Alleged Prion Discharges into Ames Sewer System

http://www.city.ames.ia.us/waterweb/NADC/NADC.htm

NADC Waste Water Disposal Evaluation

Report of the Scientific Review Panel - November 21, 2006 (pdf)

Excerpts from scientific studies on inactivation of TSE infectivity by "steam sterilization" NEW

In the Matter of the NADC Waste Disposal Evaluation - Transcript of Public Presentation of Findings

City of Ames, Iowa - November 17, 2006 (pdf)

In the Matter of the NADC Waste Disposal Evaluation - Transcript of Telephone Conference Call

City of Ames, Iowa - November 3, 2006 (pdf)

In the Matter of the NADC Waste Disposal Evaluation - Transcript of Telephone Conference Call

City of Ames, Iowa - October 18, 2006 (pdf)

In the Matter of the NADC Waste Disposal Evaluation - Transcript of Initial Public Meeting

City of Ames, Iowa - August 23, 2006 (pdf)

Review panel looks at NADC waste disposal in Ames

Radio Iowa - August 23, 2006

NADC Waste Disposal Evaluation - Scientific Review Panel Charter

August 23, 2006 (pdf)

Federal Register Notice of Meeting and Supplementary Information

Dept. of Agriculture - Agricultural Research Service - Office of the Under Secretary, Research, Education, and Economics; Notice of the Scientific Review Panel at the National Animal Disease Center, Ames, IA - August 16, 2006

Waste dispute threatens disease lab's work

Des Moines Register - June 18, 2006

Team of Experts Named to Examine NADC Procedures

City of Ames, Iowa - June 2, 2006 (pdf)

Statement by Dr. Caird Rexroad, Associate Administrator of the Agricultural Research Service

May 11, 2006 (pdf)

City Manager’s Statement

City of Ames, Iowa - May 11, 2006 (pdf)

Email from Richard Auwerda, NADC Animal Caretaker Supervisor to USDA Inspector General - May 9, 2006

Email from Richard Auwerda, NADC Animal Caretaker Supervisor to John Dunn, Asst. Director Ames Water & Pollution Control Dept. - May 9, 2006

Email from John Dunn, Asst. Director Ames Water & Pollution Control Dept. to Richard Auwerda, NADC Animal Caretaker Supervisor - May 9, 2006

Email exchange between Marcus Kehrli, NADC Research Leader and Richard Auwerda, NADC Animal Caretaker Supervisor - March 28-29, 2006

Email from Richard Auwerda, NADC Animal Caretaker Supervisor to Robert Stoker, NADC Industrial Hygiene and Safety Manager - March 28, 2006

Email from Marcus Kehrli, NADC Research Leader to David Alt, NADC Veterinary Medical Officer and Richard Auwerda, NADC Animal Caretaker Supervisor - February 28, 2006

Email from David Alt, NADC Veterinary Medical Officer to Richard Auwerda, NADC Animal Caretaker Supervisor - February 28, 2006

Email from Richard Auwerda, NADC Animal Caretaker Supervisor to Ronald Morgan, Head of APHIS Animal Resources/NVSL - February 28, 2006

Email from Ronald Morgan, Head of APHIS Animal Resources/NVSL to Richard Auwerda, NADC Animal Caretaker Supervisor - February 28, 2006

Email from Michelle Crocheck, NVSL Veterinary Medical Officer to Richard Auwerda, NADC Animal Caretaker Supervisor - February 28, 2006

Email from Richard Auwerda, NADC Animal Caretaker Supervisor to Michelle Crocheck, NVSL Veterinary Medical Officer - February 28, 2006

Research Project: IDENTIFICATION OF CATTLE WITH DIFFERENT GENOTYPES FOR BSE INOCULATION

USDA - Agricultural Research Service/NADC - February 15, 2007

Research Project: IDENTIFICATION OF CATTLE WITH DIFFERENT GENOTYPES FOR BSE INOCULATION - 2006 Annual Report

USDA - Agricultural Research Service/NADC - February 15, 2007

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Discharges of Laboratory Waste to Publicly-Owned Treatment Works (POTWs) - DRAFT

Industrial Pretreatment Program - US Environmental Protection Agency Region 8 - May 4, 2003 (pdf)

Inactivation of Transmissible Degenerative Encephalopathy Agents: A Review - D.M. Taylor

Veterinary Journal - 2000 (pdf)

Virus-Like Sensitivity of the Scrapie Agent to Heat Inactivation - Rohwer

Science - February 1984 (pdf)

Comparative Analysis of Scrapie Agent Inactivation Methods - Ernst and Race

Journal of Virological Methods - 1993 (pdf)

FINAL OPINION AND REPORT ON : A TREATMENT OF ANIMAL WASTE BY MEANS OF HIGH TEMPERATURE (150°C, 3 HOURS) AND HIGH PRESSURE ALKALINE HYDROLYSIS.

European Commission - Scientific Steering Committee - April 10, 2003 (pdf)

BEST MANAGEMENT PRACTICES FOR HANDLING SUSPECT BIOSAFETY LEVEL 2 ANIMAL TRANSMISSIBLE SPONGIFORM ENCEPHALOPATHY (TSE) DIAGNOSTIC SAMPLES (SCRAPIE, CHRONIC WASTING DISEAS E AND TRANSMISSIBLE MINK
ENCEPHALOPATHY) IN ANIMAL HEALTH LABORATORIES

American Association of Veterinary Laboratory Diagnosticians - February 18, 2004

Biosafety in Microbiological and Biomedical Laboratories - Fourth Edition

U.S. Department of Health and Human Services Public Health Service - Centers for Disease Control and Prevention - April 1999 (pdf)

Thermostability of mouse-passaged BSE and scrapie is independent of host PrP genotype implications for the nature of the causal

agents - Taylor, et al.

Journal of General Virology - 2002 (pdf)

Characterization of Thermodynamic Diversity between Transmissible Spongiform Encephalopathy Agent Strains and Its Theoretical Implications - Somerville, et al.

Journal of Biological Chemistry - March 29, 2002 (pdf)

Comments on FDA Proposed Rulemaking - Docket No. 2002N-0273

Waste Reduction by Waste Reduction, Inc. - 2006 (pdf)

Recovery of Infectious Prion Protein from Environmental Samples - Bartholomay, et al.

The Second International Chronic Wasting Disease Symposium - Madison, Wisconsin - July 12 – 14, 2005 (abstract)

Environmental Sources of Prion Transmission in Mule Deer - Miller, et al.

Emerging Infectious Diseases - June 2004 (pdf)

http://www.cwd.cc/NADC_waste_disposal.htm

Excerpts from scientific studies on inactivation of TSE infectivity by "steam sterilization"

TSE-contaminated wastewater from the NADC's labs, necropsy buildings, and animal containment buildings are treated as follows: "Stored waste water is next transferred to one of four heat treatment cook tanks (6,500 gallons each) that uses direct steam injection, at 250 degrees F (121 degrees C), at one atmosphere of pressure with a batch retention time of 30 minutes." Source: NADC Waste Water Disposal Evaluation - Report of the Scientific Review Panel - November 21, 2006. It should be noted that the panel's report did not reference a single scientific study to support its conclusion that "the NADC waste water pretreatment facility as designed and operated should be an effective process to inactivate TSE infectivity." In fact there are no published studies evaluating the efficacy of this specific process. There are, however, numerous studies of various physical and chemical inactivation methods, including autoclaving which is the application of superheated steam under pressure. The following excerpts are taken from peer-reviewed studies and scientific literature reviews and address the limitations of autoclaving for inactivation of TSE infectivity. JW

"High-titered (greater than 10(10) LD50 [50% lethal dose[/g) preparations of scrapie virus-infected hamster brain were subjected to inactivation by various chemicals, autoclaving, and histopathologic processing....One hour in an autoclave at 121 C reduced the titer of scrapie virus by approximately 7.5 log LD50/g of brain but left 2.5 log LD50/g of residual infectivity. A combination of exposure to chemicals and autoclaving may be necessary to sterilize high-titered scrapie virus-infected tissue." P. Brown, R.G. Rohwer, E.M. Green, D.C. Gajdusek. 1982. Effect of chemicals, heat, and histopathologic processing on high-infectivity hamster-adapted scrapie virus. Journal of Infectious Diseases 145(5):683-7.

"Autoclaving at 132 degrees C for 90 min completely eliminated the detectable infectivity, and was at least 100-fold more effective than 121 degrees C for 60 min. Although earlier reports stated that the scrapie agent contained in hamster brain homogenate can be destroyed by exposure to 132 degrees C for 60 min (Brown, et al., 1986), our data show that exposure to 132 degrees C for 60 min did not eliminate all the infectivity from the infected hamster brain homogenate....

Therefore, inactivation potentials by autoclaving may vary in different situations, and can be regarded as a treatment to lower titers of agent, but on the basis of our data, it is not safe to say that autoclaving sterilizes high titers of scrapie agent." D.R. Ernst, R.E. Race. 1993. Comparative analysis of scrapie agent inactivation methods. Journal of Virological Methods 41:193-202.

"Autoclaving at 126 degrees C for 1-2 h reduced titres by 10(3)-10(7) units, depending on the strain of agent. However, total disinfection of brain containing high titres of infectivity was approached only at 136 degrees C when titre losses of about 10(6) units were obtained by autoclaving for 4-32 min. Further studies are needed before we can make simple, general recommendations for the disinfection of CJD agents in hospital practice." R.H Kimberlin, C.A. Walker, G.C. Millson, D.M. Taylor, P.A. Robertson, A.H Tomlinson, A.G Dickinson. 1983. Disinfection studies with two strains of mouse-passaged scrapie agent. Guidelines for Creutzfeldt-Jakob and related agents. Journal of the Neurological Sciences 59(3):355-69.

"The resistance of small subpopulations of scrapie infectivity to inactivation at 100°C dictates against the use of boiling for disinfection of scrapie-contaminated material. Resistant subpopulations can also exist at 121°C (1, 2, 6, 8, 9). In other experiments we have recovered small amounts of infectivity from a sample exposed to 121°C for 60 minutes in an autoclave (1). The surviving population represented only 0.000002 percent of the starting infectivity. Nevertheless, this result suggests caution in the use of autoclaves for disinfection of scrapie and other members of this class of agents (1, 3, 21)." R.G. Rohwer. 1984. Virus-Like Sensitivity of the Scrapie Agent to Heat Inactivation. Science 223:600-602.

"Macerates of bovine brain infected with bovine spongiform encephalopathy (BSE) agent, and rodent brain infected with the 263K or ME7 strains of scrapie agent, were subjected to porous-load autoclaving at temperatures between 134 and 138 degrees C for < or = 60 min. Bioassay in rodents showed that none of the regimens produced complete inactivation." D.M. Taylor, H. Fraser, I. McConnell, D.A. Brown, K.L. Brown, K.A. Lamza, G.R. Smith. 1994. Decontamination studies with the agents of bovine spongiform encephalopathy and scrapie. Archives of Virology 139(3-4):313-26.

"Prions are very resistant to inactivation, and accidental transmission has occurred through the use of inadequate decontamination procedures....Infectivity can survive autoclaving at 132-138 degrees C, and under certain conditions the effectiveness of autoclaving actually declines as the temperature is increased. The small resistant subpopulations that survive autoclaving are not inactivated by simply re-autoclaving, and they acquire biological characteristics that differentiate them from the main population." D.M. Taylor. 1999. Inactivation of prions by physical and chemical means. Journal of Hospital Infection 43 Suppl:S69-76.

"Samples of macerated mouse-brain infected with the 22A strain of scrapie agent were subjected to gravity-displacement autoclaving at 121 degrees C for 30 minutes in the presence of 2 M sodium hydroxide. No infectivity was detectable by mouse bioassay in samples which were either held for an hour at room temperature before autoclaving, or autoclaved immediately after adding the hydroxide. In contrast, all of the mice injected with a control sample, held for an hour in distilled water before autoclaving, developed scrapie." D.M. Taylor, K. Fernie, I. McConnell. 1997. Inactivation of the 22A strain of scrapie agent by autoclaving in sodium hydroxide. Veterinary Microbiology 58(2-4):87-91.

"In the studies carried out so far, the BSE agent has proved to be just as resistant as other TSE agents to inactivation by procedures such as autoclaving or exposure to sodium hydroxide that are effective with conventional microorganisms...Despite the survival of BSE infectivity after autoclaving or exposure to sodium hydroxide, it is known that combining these procedures results in a very reliable degree of inactivation for TSE agents generally." D. Taylor. 2002. Inactivation of the BSE agent. Comptes rendus biologies 325(1):75-6.

"GD (gravity-displacement) autoclaving at 121 degrees C for 90 min reduced the titre of 263K (hamster-passaged scrapie) by 6 logs, but 3.4 logs survived (Prusiner, et al., 1984). This is in good agreement with the data obtained by Ernst and Race (1993) using the same agent and the same autoclaving regime, showing a 5.7 log reduction. Autoclaving the same agent at 134 degrees C for 30 min reduced the titre by 5.3 logs, but 3.5 logs survived (Brown, et al., 1990a). Autoclaving at 126 degrees C for 2 hours inactivated 139A (mouse-passaged scrapie) but not 22A (mouse-passaged scrapie) (Kimberlin, et al., 1983), which was inactivated only after a 4 hour exposure (Dickinson 1976)." D.M. Taylor. 2000. Inactivation of Transmissible Degenerative Encephalopathy Agents: A Review. The Veterinary Journal 159, 10-17.

"TSE agent strains show variability in their sensitivity to heat (Kimberlin et al., 1983; Somerville et al., 2002) although they are all difficult to inactivate by heating in an aqueous environment such as an autoclave...Although it is possible to achieve full inactivation (Rohwer, 1984), in some circumstances significant amounts of infectivity survive (Taylor et al., 1998)...Five experimentally maintained strains of scrapie and BSE agents have been passaged in two PrP genotypes of mice. Brain macerates were autoclaved at 126 °C and the levels of surviving infectivity were measured by titration. There was a large difference in the survival properties of transmissible spongiform encephalopathy (TSE) infectivity between TSE strains." D.M. Taylor, K. Fernie, P.J. Steele, I. McConnell, R.A. Somerville. 2002. Thermostability of mouse-passaged BSE and scrapie is independent of host PrP genotype: implications for the nature of the causal agents. Journal of General Virology 83, 3199–3204.

http://www.cwd.cc/Excerpts_from_studies_on_steam_sterilization.htm

TSS




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